Wearable health monitoring has garnered considerable interest from the healthcare industry as an evolutionary alternative to standard practices with the ability to provide rapid, off‐site diagnosis and patient‐monitoring. In particular, sweat‐based wearable biosensors offer a noninvasive route to continuously monitor a variety of biomarkers for a range of physiological conditions. Both the accessibility and wealth of information of sweat make it an ideal target for noninvasive devices that can aid in early diagnosis of disease or to monitor athletic performance. Here, the integration of ammonium (NH4+) and calcium (Ca2+) ion‐selective membranes with a poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)‐based (PEDOT:PSS) organic electrochemical transistor (OECT) for multiplexed sensing of NH4+and Ca2+in sweat with high sensitivity and selectivity is reported for the first time. The presented wearable sweat sensor is designed by combining a flexible and stretchable styrene‐ethylene‐butene‐styrene substrate with a laser‐patterned microcapillary channel array for direct sweat acquisition and delivery to the ion‐selective OECT. The resulting dermal sensor exhibits a wide working range between 0.01 × 10−3and 100 × 10−3
Complex graphene electrode fabrication protocols including conventional chemical vapor deposition and graphene transfer techniques as well as more recent solution‐phase printing and postprint annealing methods have hindered the wide‐scale implementation of electrochemical devices including solid‐state ion‐selective electrodes (ISEs). Herein, a facile graphene ISE fabrication technique that utilizes laser induced graphene (LIG), formed by converting polyimide into graphene by a CO2laser and functionalization with ammonium ion (NH4+) and potassium ion (K+) ion‐selective membranes, is demonstrated. The electrochemical LIG ISEs exhibit a wide sensing range (0.1 × 10−3–150 × 10−3
- PAR ID:
- 10457607
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials Technologies
- Volume:
- 5
- Issue:
- 6
- ISSN:
- 2365-709X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract m , well within the physiological levels of NH4+and Ca2+in sweat. The integrated devices are successfully implemented with both ex situ measurements and on human subjects with real‐time analysis using a wearable sensor assembly. -
null (Ed.)Cost-effective valorization of biomass into advanced carbon remains a challenge. Here we reported a facile and ultrafast laser writing technique to convert biomass into porous graphene for electrochemical sensing. Laser-induced graphene (LIG) was synthesized from a fully biomass-based film composed of kraft lignin (KL) and cellulose nanofibers (CNFs). The LIG-based electrode was applied to detect dopamine using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Dopamine with a concentration ranging from 5 to 40 μM was detected linearly, with a sensitivity of 4.39 μA μM −1 cm −2 . Our study eliminated the use of synthetic polymer for lignin-based film formation. It demonstrated the feasibility of using the film fully composed of biomass for LIG formation. Furthermore, derived LIG electrodes were shown to have high electrochemical sensing performance.more » « less
-
more » « less
Abstract Glyphosate is a globally applied herbicide yet it has been relatively undetectable in‐field samples outside of gold‐standard techniques. Its presumed nontoxicity toward humans has been contested by the International Agency for Research on Cancer, while it has been detected in farmers’ urine, surface waters and crop residues. Rapid, on‐site detection of glyphosate is hindered by lack of field‐deployable and easy‐to‐use sensors that circumvent sample transportation to limited laboratories that possess the equipment needed for detection. Herein, the flavoenzyme, glycine oxidase, immobilized on platinum‐decorated laser‐induced graphene (LIG) is used for selective detection of glyphosate as it is a substrate for GlyOx. The LIG platform provides a scaffold for enzyme attachment while maintaining the electronic and surface properties of graphene. The sensor exhibits a linear range of 10–260
µ m , detection limit of 3.03µ m , and sensitivity of 0.991 nAµ m −1. The sensor shows minimal interference from the commonly used herbicides and insecticides: atrazine, 2,4‐dichlorophenoxyacetic acid, dicamba, parathion‐methyl, paraoxon‐methyl, malathion, chlorpyrifos, thiamethoxam, clothianidin, and imidacloprid. Sensor function is further tested in complex river water and crop residue fluids, which validate this platform as a scalable, direct‐write, and selective method of glyphosate detection for herbicide mapping and food analysis. -
Ion selective electrode (ISE) sensors have been broadly applied for real-time in situ monitoring of ion concentrations in water environments. However, ISE sensors suffer from critical problems, such as ionophore leaching, water-penetration, poor electrochemical stability, and resulting short life spans. In this study, a template-guided membrane matrix immobilization strategy was pursued as a novel ISE sensor fabrication methodology to enhance its sensing characteristics and longevity. Specifically, nano-porous anodized aluminum oxide (AAO) was used as the template for an NH 4 + -specific ISE sensor. A nano-porous nickel mesh eventually replaced the template and formed a compact, high-surface juncture with the NH 4 + ion-selective membrane matrix. The resulting template-guided nano-mesh ISE (TN-ISE) sensor displayed enhanced electrochemical stability ( i.e. , capacitance increased by 50%, reading drift reduced by 75%) when compared to a regular single-wall carbon nanotube (SW-CNT) ISE sensor used as the standard. The interface between the nano-mesh electrode and the ion selective membrane matrix was compact enough to prevent water influx at the electrode interface. This minimized ionophore leaching and increased the mechanical integrity of the TN-ISE sensor. The practical advantages of the novel sensor were validated via long-term (360 hours) tests in real wastewater, returning a small average error of 1.28% over this time. The results demonstrate the feasibility of the template-guided nano-mesh design and fabrication strategy toward ISEs for long-term continuous monitoring of water or wastewater quality.more » « less
-
more » « less
Abstract Nitrogen and phosphorus‐containing ions such as ammonium, nitrates and phosphates are anthropogenic pollutants while ammonium nitrate may be diverted for nefarious purposes in improvised explosive devices. Crown ether‐oxoporphyrinogen conjugates (
OxP ‐crowns) are used to selectively detect nitrates, especially their ion pairs with K+and NH4+, based on ion pair complexation ofOxP ‐crowns under phase transfer conditions. The presence of phosphate and carbonate lead to deprotonation ofOxP ‐crowns.OxP‐1N18C6 is capable of extracting ion pairs with nitrate from aqueous phase leading to a selective chromogenic response. Deprotonation of theOxP moiety leads to [OxP −]‐1N18C6 [K+] and is promoted by crown ether selective cation binding coupled with hydration of basic oxoanions, which are constrained to remain in the aqueous phase. This work illustrates the utility of molecular design to exploit partitioning and ion hydration effects establishing the selectivity of the chromogenic response.
